1. Field of the Invention
The invention is a clock spring housing for enclosing an electrical connector, the clock spring housing uniting a rotatable portion of the electrical connector to a stationary portion of the electric connector. This invention is also a clock spring assembly, that is the clock spring housing including the electrical circuit.
An increasing number of automobiles have air bag crash systems. An air bag is typically located on the steering wheel facing the driver. The air bag must be in continuous electrical connection with sensors in the car body. The sensors provide an electrical signal to the air bag crash assembly which instantly inflates the air bag in the event of a crash.
Accordingly, there is a need for an electrical connection between the rotatable portion of the air bag assembly which is mounted on the steering wheel, and the remaining portion of the assembly which is in a stationary position in the car body. Electrical connections between rotatable and stationary parts are well known. Typically, an electrical brush rests upon a conductive ring, with one of the parts being rotatable to provide such rotatable electrical connection. However, there is a risk, particularly during the impact of an accident, of a transient failure of electrical connection with a brush and ring system, which would result in failure of the entire air bag system crash assembly.
Accordingly, a clock spring interconnector has been previously developed, comprising an outer housing and a rotor member, the housing and rotor member rotatably associated with one another at a plurality of bearing surfaces. A "clock spring" is located inside the interconnector, the clock spring conductively attached at both ends to conductor wires which pass out of the interconnector to unite the air bag to the sensing device. The interconnector is mounted on the steering column, and the steering wheel may be rotated in either direction while a continuous, positive electrical connection is provided between air bag and sensors via the clock spring interconnector.
While prior art clock spring interconnectors are effective to provide the necessary continuous electrical connection between an air bag or other device on a rotating column and a stationary portion of a circuit, the prior art systems are subject to noise, binding, and in some cases failure as a result of having a plurality of bearing surfaces working in concert.
2. Prior Art
U.S. Pat. No. 4,722,690 describes a clock spring interconnector which includes a projection for ensuring that the rotating portion of the clock spring assembly remains stationary during installation of the assembly onto a steering wheel. The assembly of the '690 patent comprises two bearing surfaces where the rotating portions of the assembly contacts the stationary assembly housing.